The present invention relates to latches and latching methods, and more particularly to devices and methods for controlling and switching a latch between latched and unlatched states and to actuators useful for accomplishing these functions.
Conventional latches are used to restrain the movement of one member or element with respect to another. For example, conventional door latches restrain the movement of a door with respect to a surrounding door frame. The function of such latches is to hold the door secure within the frame until the latch is released and the door is free to open. Existing latches typically have mechanical connections linking the latch to actuation elements such as handles which can be actuated by a user to release the latch. Movement of the actuation elements is transferred through the mechanical connections and will cause the latch to release. The mechanical connections can be one or more rods, cables, or other suitable elements or devices. Although the following discussion is with reference to door latches (e.g., especially for vehicle doors) for purposes of example and discussion only, the background information provided applies equally to a wide variety of latches used in other applications.
Most current vehicle door latches contain a restraint mechanism for preventing the release of the latch without proper authorization. When in a locked state, the restraint mechanism blocks or impedes the mechanical connection between a user-operable handle (or other door opening device) and a latch release mechanism, thereby locking the door. Many conventional door latches also have two or more lock states, such as unlocked, locked, child locked, and dead locked states. Inputs to the latch for controlling the lock states of the latch can be mechanical, electrical, or parallel mechanical and electrical inputs. For example, by the turn of a user""s key, a cylinder lock can mechanically move the restraint mechanism, thereby unlocking the latch. As another example, cable or rod elements connecting a door handle to the latch release mechanism can be controlled by one or more electrical power actuators. These actuators, sometimes called xe2x80x9cpower locksxe2x80x9d can use electrical motors or solenoids as the force generator to change between locked and unlocked states.
A number of problems exist, however, in the conventional door latches described above. For example, conventional restraint mechanisms in such latches are typically quite complex, with numerous parts often having relatively complicated movements. Such latches are thus more expensive to manufacture, assemble, maintain, and repair. This problem is compounded in latches having multiple lock states as mentioned above. These latches often require separate sets of elements corresponding to and controlling each lock state of the latch.
In addition, because conventional door latches are typically relatively complex (especially latches having multiple lock states), the ability of a latch design to be used in diverse applications suffers significantly. For example, many conventional door latches are suitable for installation in a particular door, but cannot readily be installed in other door designs. As another example, door latch applications in which only limited latching functions are needed generally call for a different door latch than door latch applications in which full latching functions are needed. Conventional door latches are far from being xe2x80x9cuniversalxe2x80x9d (capable of installation in a number of different applications and easily adaptable to applications varying in functionality). Therefore, it is often necessary for a manufacturer, installer, or servicer of door latches to keep a wide variety of different door latches in inventoryxe2x80x94an expensive and inefficient practice.
Space and location constraints for door latches varies significantly from application to application. In some applications for example, connecting rods are used to mechanically link door handles or user-operable lock buttons to the latch, while in other applications bowden cables are more suitable. As used herein and in the appended claims, the terms xe2x80x9cuser-operablexe2x80x9d, xe2x80x9cuser-actuatablexe2x80x9d, and the like include direct and indirect user operation and actuation. Therefore, devices or elements described in such manner include those that are operated upon or actuated indirectly by a user in some manner (e.g., via electronic actuation, mechanical linkage, and the like), and are not necessarily limited to devices or elements intended for direct contact and manipulation by a user in normal operations of the latch.
The latch space and location constraints mentioned above can also require latch connections to be made only from certain sides or the latch or only at certain angles with respect to portions of the latch. Conventional latch manufacturers address such problems by providing specialized latches for specific applications or groups of applications. Once again, this solution requires a manufacturer, installer, or servicer of door latches to incur the expense of keeping a wide variety of different door latches in inventory.
For obvious reasons, increased latch complexity also has a significant impact upon assembly and repair cost. Conventional door latches are generally difficult to assemble and require a significant amount of assembly time. An assembler must often orient the latch assembly in several directions during the assembly process (i.e., flip the latch over or turn the latch repeatedly). Also, the large number of small and intricate parts typically used in conventional door latches adds to assembly cost. Particularly in light of the specialized nature, function, and redundancy of many door latch parts, conventional door latches designs are far from being optimized.
Problems of latch weight and size are related to the problem of latch complexity. The inclusion of more elements and more complex mechanisms within the latch generally undesirably increases the size and weight of the latch. In virtually all vehicle applications, weight and size of any component is a concern. Additionally, increased weight and size of elements and assemblies within the latch necessarily requires more power and greater force to operate the latch. Because power is also at a premium in many applications (especially in vehicular applications), numerous elements and complex assemblies within conventional door latches are an inefficiency that is often wrongly ignored. Not only are larger and more complex latches a power drain, but such latches are typically unnecessarily slow.
Latch operating speed continues to be important to the latch design viability, particularly with the increasingly common use of electromechanical assemblies in many latch applications. The time required to perform each latch operation has been reduced to well under one second in vehicular applications, and significant advantages exist for reducing such time even further. Specifically, it is most desirable to reduce the amount of time to change the state of a latch, such as from a locked state to an unlocked state, from a child-locked state to an unlocked state, etc. Although numerous conventional mechanisms exist for accelerating latch state changes, the speed at which such changes are performed remains far from optimal. This is due at least in part to the incremental improvement of conventional mechanical assemblies in lieu of using significantly different mechanisms and devices for changing latch states. Also, compact actuation devices capable of very rapidly and significantly changing the state of a mechanical assembly are not common. Such actuation devices that do exist are often not suitable for use in mechanical devices having moving and inertial forces that are significantly larger than the actuation device itself (as is the case with many types of latches).
Another problem with conventional door latches relates to their operation. Particularly where a latch has multiple lock states, the ability of a user to easily and fully control the latch in its various lock states is quite limited. For example, many latches having a child locked state (i.e., the inside door handle is disabled but the outside door handle is not) require a user to manually set the child locked state by manipulating a lever or other device on the latch. Other latches do not permit the door to enter a dead locked state (i.e., both the inside and outside door handles being disabled). Also, conventional door latches generally do not permit a user to place the door latch in all lock states remotely, such as by a button or buttons on a key fob. These examples are only some of the shortcomings in existing door latch operability.
Still another problem of conventional door latches is related to power locks. The design of existing power lock systems has until now significantly limited the safety of the latch. Latch design limitations exist in conventional latches to ensure, for example, that dead locked latches operated by powered devices or systems will reliably unlock in the event of power interruption or failure. Such limitations have resulted in latch designs which permit less than optimal user operability. Although manual overrides for conventional door latches do exist, these overrides typically add a significant amount of complexity to the door latch and are difficult to install and assemble. Therefore, a reliable design having a failure mode and a simple manual override for an electrically powered latch which is electrically actuatable in all locked states remains an elusive goal.
In conventional door latches, yet another problem is caused by the fact that an unauthorized user can often manipulate the restraint mechanism within the latch and/or the connections of the latch to the door locks to unlock the latch. Because conventional door latches typically have at least some type of mechanical linkage from the user-operable elements (e.g., lock cylinders) to the restraint mechanism in the latch, the ability of an unauthorized user to unlock the latch as just described has been a persistent problem. Many existing door latches have multiple paths through which force is transmitted from a user-operable device to the restraint mechanism in the latch. For example, where the restraint mechanism is a ratchet selectively held in a locked position by a movable pawl, conventional door latches have multiple direct and/or indirect connections to the pawl from multiple user-operable devices. Each such connection added to a latch assembly provides another latch input that is subject to manipulation by an unauthorized user to unlock the latch. Although multiple connections are necessary to full latch functionality, many existing latch designs employ separate and independent connections without regard for the ability to reduce the number of force transmitting paths into the latch.
As described above, inputs to latch assemblies typically include one or more user-operable devices such as handles, buttons, levers, and the like for releasing the latch restraint mechanism and one or more user-operable devices such as lock cylinders, sill buttons, and the like for changing the lock state of the latch. The conventional practice of employing separate connections to the latch for such inputs increases latch complexity, weight, and expense, and increases the design difficulty in selectively disabling or isolating any particular input as desired.
In light of the problems and limitations of the prior art described above, a need exists for a latch assembly which can be used in many applications, is modular and which therefore has easily adaptable functionality to meet the needs of a large number of applications (i.e., from limited to full functionality), has the fewest elements and assemblies possible, is smaller, faster, and lighter than existing latches, consumes less power in operation, is less expensive and easier to manufacture, assemble, maintain, and repair, provides a high degree of flexibility in user operation to control the lock states of the latch, has a simple and reliable design for manual override in the event of power interruption or failure, offers improved security against unlocking by an unauthorized user, has as few inputs as possible for unlatching the latch while still retaining full latch functionality, and provides the ability to quickly isolate desired combinations of latch inputs. A need also exists for an actuation device that is compact, fast, capable of rapidly changing the states of a mechanical device (such as a latch), and is operable significantly independent of the size of device input and inertial forces. Each preferred embodiment of the present invention achieves one or more of these results.
The latch assembly of the present invention is preferably capable of receiving a number of external inputs used to control the operation and state of the latch. Preferably, these inputs are connected to one or more user-operable devices for releasing the latch and to one or more user-operable devices for changing the state of the latch (e.g., to and between latch states such as unlocked, locked, child locked, and dead locked, states). Although multiple inputs can run to the latch assembly, preferably only a limited number of paths exist through the latch for releasing the latch. In a preferred embodiment of the invention, the element or mechanism directly generating release of the latch (e.g., a fork bolt or a ratchet releasably engaged with a striker bar) is acted upon through one path shared by two or more inputs to the latch. In other words, where conventional latch assemblies typically employ multiple inputs connected xe2x80x9cin parallelxe2x80x9d to the element or mechanism directly generating release of the latch, the inputs of this embodiment of the present invention are preferably connected to this element or mechanism xe2x80x9cin seriesxe2x80x9d. Fewer separate and independent latch releasing paths through the latch assembly result in a latch that is more resistant to unauthorized release, less complex, requires fewer elements and components, and is less expensive to manufacture, assemble, service, and maintain than its conventional counterparts.
In highly preferred embodiments of the latch assembly of the present invention, unlocked and locked states of the latch assembly are established by at least two different types of movement of a control element. The control element moves in a first manner through a first path when the latch assembly is in an unlocked state and in a second manner through a second path when the latch assembly is in a locked state. As used herein and in the appended claims, movement of an element in or through a path does not necessarily mean that the element moves fully through the path available to it, such as from one extremity of the path to another. Instead, movement of an element in or through a path means that the element moves at least partially in or through the path available to it. When the control element moves in the first manner, the control element imparts motion either directly or indirectly to a latch element or mechanism (e.g., a ratchet). Such motion moves the latch element or mechanism to move to its unlatched position to unlatch the door. In contrast, when the control element moves in a second manner, the control element does not impart motion (or sufficient motion) to the latch element or mechanism for unlatching the door. Therefore, whether movement or actuation of the control element by a user will unlatch the latch depends upon whether the control element moves in the first or the second manner. The latch assembly of the present invention operates to quickly change the manner of control element motion by preferably extending or retracting one or more elements that guide or limit the motion of the control element. These elements are preferably pins which are quickly extended and retracted by one or more actuators, although other elements can be used effectively.
A highly preferred embodiment of the present invention has two control elements, pins, and actuators. Each control element, pin, and actuator set is preferably connected to and corresponds to at least one input to the latch assembly, such as to a user-operable handle, lever, lock cylinder, sill button, etc. Most preferably, each control element, pin, and actuator set is coupled to a respective door handle. In each control element, pin, and actuator set, the actuator can be extended to insert the pin into an aperture in the control element and can also be retracted to retract the pin from the aperture. When the actuator and pin are extended and thereby engage the control element, the control element preferably pivots through a first path about a first pivot point. However, when the actuator and pin are retracted and are thereby disengaged from the control element, the control element preferably pivots through a second path about a second pivot point. Movement of the control element through the first path preferably brings the control element into contact with a pawl that is coupled to the latch element or mechanism. This contact causes the latch element or mechanism to release, thereby unlatching the door. The control element in the first path is therefore is in an unlocked state. In contrast, movement of the control element through the second path preferably does not bring the control element into such contact, or at least into contact sufficient to release the latch element or mechanism. The control element in the second path therefore is in a locked state.
In some embodiments of the present invention, each control element is connected to a respective user-operable input and is movable in its unlocked state to contact the pawl and to release the ratchet. In these embodiments, each control element does not rely upon another control element for latch release. The user-operable inputs connected to the control elements in these embodiments are therefore xe2x80x9cin parallelxe2x80x9d as described above because each can separately and independently generate latch release. However, the user-operable inputs in other embodiments of the present invention are connected xe2x80x9cin seriesxe2x80x9d as also described above. Where two control element, pin, and actuator sets are used with respective user-operable inputs, actuation of a first control element in its unlocked state preferably releases the ratchet without substantial interaction with the second control element. Actuation of the second control element in its unlocked state preferably releases the ratchet only via contact and force transmission through the first control element in its unlocked state. In another similar embodiment, the second control element is always in its unlocked state, and depends upon the state of the first control element to transmit ratchet-releasing force therethrough. Still other embodiments of the present invention employing multiple latch inputs connected xe2x80x9cin seriesxe2x80x9d via two or more control elements are possible. In each such embodiment, the latch assembly preferably has more latch-releasing inputs (e.g., door handles, levers, and the like) than control elements capable of releasing the ratchet without required actuation of another control element.
In highly preferred embodiments of the present invention, the actuators are electromechanical solenoids that perform quick retraction and extension operations to engage and disengage the control elements in their different lock states. The control elements preferably pivot about an aperture in each control element that is engaged by the pin in the extended position and about another pivot point or about post, peg, or other element extending from each control element when the pin is not engaged therewith.
In referring herein to xe2x80x9cretractionxe2x80x9d and xe2x80x9cextensionxe2x80x9d operations of solenoids and to xe2x80x9cretractedxe2x80x9d and xe2x80x9cextendedxe2x80x9d positions of the solenoids, it should be understood that this is with reference to well known operation of conventional solenoids. Specifically, solenoids typically have one or more elements (such as an armature) which are controllable to extend and retract from the remainder of the solenoid in a well known manner. Terms such as retraction, retracted, extension and extended used herein in connection with a solenoid refers to such conventional solenoid operations. It will be apparent that modified solenoids or other actuators, or even other actuating devices such as mini-motors, devices made of shape memory alloys (such as muscle wires), vacuum cylinders, etc. can be used without departing from the present invention.
Other advantages of the present invention are provided by an actuator employing magnetic force to engage and restrain one or more elements. This actuator is a solenoid having at least one coil that can be energized to extend or retract an armature of the actuator (to engage or disengage from one or more elements, respectively). The armature can be biased in an opposite direction by a conventional spring or other bias element, but most preferably is moved in an opposite direction by energization of a second coil. To increase the speed at which the actuator engages an element, the actuator includes a holding element at an end thereof. The holding element is at least partially made of a ferrous material, ferromagnetic material, and/or any material otherwise attracted or repelled by a magnetic field (hereinafter and in the appended claims referred to as xe2x80x9cmagneticxe2x80x9d material). The holding element has at least an engaged state in which holding element movement is impeded by magnetic force from the energized first coil and a disengaged state in which the holding element can move more freely because the first coil is less energized or is not energized.
By energizing the first coil as described above, movement of the holding element can be impeded, and is most preferably restrained. Specifically, the holding element can be attracted or repelled by the first coil""s magnetic force against the latch housing, against the coil itself, or against another element in the latch, thereby impeding further holding element movement. The movement of any element engaged with or connected to the holding element is therefore also impeded. To this end, the holding element most preferably has a pin that is engaged with a connected element (e.g., a control element in the latch assembly of the present invention).
The holding element preferably has a receptacle or aperture therein for receiving the armature of the actuator. Most preferably, energization of the first coil holds the holding element in place at least until the armature has been drawn by the magnetic force into engagement with the holding element. If desired, the first coil can then be de-energized to release the holding element (and whatever other element is connected thereto), the holding element now being engaged by the armature. Alternatively, the first coil can remain energized as desired.
The time necessary to energize the first coil, generate magnetic force thereby, and exert such force upon a holding element to hold the holding element in place is significantly faster than conventional armature engagement speeds. As such, the first coil can be used to quickly hold a connected element in place via magnetic force while a slower armature is moved into engagement with the holding element or directly into engagement with the connected element. A compressible or spring-loaded armature is preferably used to help ensure reliable engagement with the holding element and/or the connected element. In most preferred embodiments of the present invention, the holding element is held by the energized first coil for a sufficient time to engage the holding element with the armature, after which time the first coil is de-energized.
Preferably, the holding element is movable through one or more tracks, guides, and the like when not restrained by the first coil. In some highly preferred embodiments of the present invention, the track is provided with a recess, seat, or depression receiving the holding element when energized by the first coil in order to help keep the holding element from moving while the armature is being drawn by the first coil. Alternatively or in addition, the track can have one or more raised portions also shaped to impede holding element movement when the first coil is energized. Preferably, the armature is thereafter held in its engaged state by an over-center spring coupled to the armature.
To disengage the holding element (and whatever element is attached thereto as desired), the first coil is preferably de-energized and the second coil is energized to draw the armature out of engagement with the holding element. The holding element and any element attached thereto is thereby able to move with respect to the coil and armature, whether in a holding element track or otherwise.
Although significant advantages are realized by using this actuator in conjunction with latch assemblies such as those described and illustrated herein, this actuator can be employed in any device and environment for selectively engaging any desired element.
The latch assembly of the present invention can employ actuators having no mechanical inputs to either extend or retract. However, in some preferred embodiments, the latch assembly can be provided with such inputs to supplement or replace actuator capabilities described above. Specifically, it can be desirable in some applications to supplement one or more powered actuators with mechanical inputs, whereby the actuators can be engaged and/or disengaged (e.g., armatures extended or retracted) by mechanical linkages to the actuators. By manually actuating a latch input to either place an actuator in its locked or unlocked state or to unlatch the latch, these mechanical linkages can transfer some of the manual force to the actuators to manually perform the engagement or disengagement operations. Where the actuators are capable of performing engagement and disengagement operations without mechanical assistance, these mechanical linkages can act as a backup feature for the actuators. Instead, these mechanical linkages permit the use of actuators requiring some degree of mechanical input (i.e., to move to one or both of the engaged or disengaged states, to move partially to an engaged state or partially from a disengaged state, and the like).
In a preferred embodiment of the present invention, a latch assembly is provided with two control elements each having a respective actuator and pin set. This latch assembly has two latch inputs for changing the state of the latch, such as between a locked to an unlocked state or between a child locked and an unlocked state. A set of levers is connected to the these inputs and is movable to mechanically attract or repel armatures of the actuators. When not otherwise disabled, actuation of the inputs causes the levers to move and to push the armatures into engagement with control elements, thereby changing the state of the latch. This motion can serve as xe2x80x9cbackupxe2x80x9d for the force provided by solenoid coils in the actuator, can supplement such force, or can even replace such force in some embodiments of the present invention. In preferred embodiments of the present invention, the connection between at least one of the inputs and the levers can be disabled to prevent the manual actuation just described.
When the latch assembly of the present invention is used on a vehicle door, a first control element is preferably coupled via a linking member to an inside door handle and a second control element is preferably coupled to an outside door handle. When the pin corresponding to each control element is extended to engage the first and second control elements, respectively, actuation of the control elements by either handle causes the actuated control element to directly or indirectly move a ratchet to unlatch the door. This is the unlocked state of the latch assembly. When the pin corresponding to each control element is retracted to disengage the first and second control elements, actuation of the control elements by either handle does not move the ratchet or does so insufficiently to unlatch the door. This is the dead locked state of the latch assembly. When the pin corresponding to the first control element is extended to engage the first control element and when the pin corresponding to the second control element is retracted to disengage the second control element, actuation of the inside door handle will directly or indirectly move a ratchet to unlatch the door, but actuation of the outside door handle will not do so. This is the locked state of the latch assembly. When the pin corresponding to the first control element is retracted to disengage the first control element and the pin corresponding to the second control element is extended to engage the second control element, actuation of the outside door handle will move the pawl and unlatch the door, but actuation of the inside door handle will not do so. This is the child locked state of the latch assembly. Of course, in other embodiments of the present invention, one, three, or even more control element, pin, and actuator sets can be used as desired.
Latch assembly operations for placing the control elements in their locked and unlocked states are therefore quickly performed via actuators, and most preferably, by electromagnetic solenoids. Also, the relatively small number of elements (e.g., an actuator, pin, control element, and, if desired, a pawl as described in more detail below) employed to place the latch assembly in its various lock states is a significant advantage over prior art latches. The latch assembly of the present invention is therefore lighter, smaller, can be operated using less power, and can be manufactured, maintained, and repaired at less expense.
In addition, the use of actuators such as electromagnetic solenoids to place the control elements in their various states provides greater flexibility for controlling the various latch assembly lock states.
The latch assembly of the present invention also preferably has a control circuit for controlling the actuators. Most preferably, the control circuit is electrical and uses a sensing device to detect changes in the primary power supply (e.g., power loss, power interruption, etc.) supplying power to the latch assembly and to the actuators. At least as a safety feature, certain changes detected in the power supply preferably cause the actuators to automatically engage the pins with the control elements and to thereby unlock the latch assembly. Because the mechanism for placing the latch assembly in its various lock states is preferably actuated electronically rather than by conventional mechanical means, the latch assembly is also more secure against unauthorized operation.
In addition to the above-noted advantages of the present invention, the latch assembly is also highly adaptable for installation in a number of different applications and in a number of different configurations, thereby providing a latch which can easily be changed from a latch having minimal functionality to a latch with full functionality, and to a number of different states in between. First, the latch assembly preferably provides linking access to the control elements therein (e.g., capability to connect the control elements to actuation elements external to the latch assembly via cables, rods, or other xe2x80x9cinputxe2x80x9d or xe2x80x9clinkingxe2x80x9d elements) either by ports for interior linking or by housing apertures permitting control elements to extend outside of the latch assembly for exterior linking. Second, the input elements linked to the latch assembly for actuation thereof are preferably fully interchangeable with multiple control elements and with the pawl. The control elements and the pawl can therefore be connected in a number of different ways to the actuation elements, thereby providing a large amount of flexibility to install the latch for operation in a variety of different ways. Third, the latch assembly preferably has a sufficient number of control element and actuator positions so that an assembler can selectively install one or more control elements and actuators in desired locations to create a latch assembly best suited for a particular application. By selecting how many control elements and associated actuators are to be installed (and where) in each particular latch, the assembler is able to easily modify each latch for a specific application without requiring any modification to the latch assembly.
The latch assemblies of the present invention preferably also have at least one manual override which permits a user to manually shift an engagement element into engagement with a control element to establish an unlocked state of the control element. Such a manual override can also or instead permit a user to manually shift an engagement element out of engagement with a control element to establish a locked state of the control element. In a highly preferred embodiment, the manual override is also capable of shifting an engagement element in such manner in response to movement of another control element in its unlocked state or in response to movement of the pawl to its unlocked state.
Another feature of the present invention is related to its assembly. Specifically, the latch assemblies are preferably assembled in layers of elements. Most preferably, a majority of elements are positioned and installed within the latch layer upon layer without requiring numerous re-orientations of the latch assembly by the assembler and without requiring access to more than one side of the latch assembly. This saves considerable assembly, service, and maintenance time, thereby lowering the cost to manufacture, service, and maintain the latch.